1. Technical Field
The present disclosure relates to a coated gut suture and, more particularly, to a coated gut suture which is capable of being dry packaged.
2. Background of the Related Art
Absorbable sutures are manufactured from natural or synthetic materials. Some of the earliest absorbable sutures were made of collagenous material taken from sheep intestines. Such sutures are still in use today and are commonly referred to as "catgut" or simply "gut" sutures or ligatures. In the present specification, the term "catgut" or "gut" suture refers to a collagen based suture or ligature of any type or origin. Gut sutures may be prepared in the form of threads or strands that are undesirably stiff before subsequent treatment which renders them flexible or pliable.
A suture having a good degree of flexibility and pliability can conform closely to body tissue without undue pressure. Good flexibility and pliability enhance the degree to which a suture can be tied down, knotted and securely placed in a desired position.
Various attempts have been made to modify and optimize the physical characteristics of gut sutures. For example, tubing fluids, i.e., liquids which are used to condition gut sutures to achieve or enhance flexibility and pliability, have been used to preserve gut sutures. Tubing fluids typically contain an alcohol such as isopropyl alcohol and a relatively small percentage of water. Examples of tubing fluids are found in U.S. Pat. Nos. 1,239,690, 2,394,054, 2,519,404, 2,524,772, and 2,694,487. Ideally, the tubing fluid aids the gut suture to retain its flexibility and pliability without adversely affecting the strength and overall integrity of the suture.
Commercially available gut sutures are immersed in tubing fluid, sterilized and supplied to surgeons in packages or tubes which contain tubing fluid. The alcohol and water present in the tubing fluid keep the suture flexible and pliable as long as they remain in contact with the suture. As the tubing fluid evaporates, the suture loses its flexibility and pliability which may affect handling characteristics.
In addition to tubing fluids, various suture coatings which adhere to the surface of the suture have been developed in an attempt to maintain flexibility and control swelling and fraying. Such coatings are also intended to improve the handling characteristics of sutures and maximize run-down performance. For example, U.S. Pat. No. 3,942,532 discloses a suture coating composition obtained by polymerizing lactones such as .epsilon.-caprolactone in the presence of a polymethylenediol. U.S. Pat. No. 4,624,256 discloses a suture coating composition containing a high molecular weight .epsilon.-caprolactone homopolymer, or a copolymer derived from a major amount of .epsilon.-caprolactone and a minor amount of a comonomer or a blend of such an .epsilon.-caprolactone polymer with a lubricating agent (e.g., sterol esters of fatty acids).
Copolymers derived from .epsilon.-caprolactone and at least one other monomer such as glycolide, lactide, p-dioxanone and trimethylene carbonate are disclosed in U.S. Pat. Nos. 4,605,730, 4,624,256, 4,700,704, 4,788,979, 4,791,929, 4,994,074, 5,076,807, 5,080,665, 5,085,629 and 5,100,433.
U.S. Pat. No. 3,896,814 discloses a dry-packaged gut suture which is coated with a treatment agent such as polyoxyethylene glycol. U.S. Pat. No. 4,027,676 discloses a gut suture coated with a three-component coating composition. This patent discloses polyalkylene glycol as one ingredient of the three-component coating composition. U.S. Pat. No. 4,506,672 discloses a gut suture coated with a cured isocyanate-capped polyester which can be packaged either dry or in alcohol-containing wrappers. U.S. Pat. No. 4,649,920 discloses an absorbable surgical suture coated with a high molecular weight poly(alkylene oxide).
The aforementioned U.S. Pat. Nos. 3,896,814, 4,027,676, 4,506,672 and 4,649,920 do not disclose a gut suture which is coated with an .epsilon.-caprolactone-containing bioabsorbable copolymer.